Impaired social functioning is a key feature of a number of neurological disorders. One core process that underlies day-to-day social functioning is the ability to think about the minds of others (Theory of Mind; ToM). Developing a detailed model of the neural computations and mechanisms underlying ToM is crucial to understanding both normal social development and illnesses such as Autism Spectrum Disorders (ASD), which are estimated by the CDC to affect roughly 1 in 110 individuals born each day. This proposal aims to develop and test a novel computational framework with which to understand ToM processing and its underlying neural mechanisms. Previous research has identified a network of brain regions believed to support ToM processing; traditional ToM paradigms from developmental and cognitive psychology, however, are not well-suited for assessing the subtle neural computations that subserve real-world ToM. Recently, researchers studying the neural basis of decision-making have employed computational modeling techniques to generate testable predictions about the specific computations underlying learning and choice behavior. This computational approach has specific advantages over traditional psychological methods. For instance, it allows for model- based fMRI, in which specific parameters can be assigned to specific neural structures, and it is better suited for a parametric approach that acknowledges variability and individual differences. Indeed, the use of computational models has proven critical for identifying the neural substrate of learning and choice behavior. At its core, the question of ToM is a question of learning (constructing a representation of other's beliefs and intentions based on their behavior) and decision-making (acting based on this stored representation); nonetheless, these cutting-edge computational modeling techniques have yet to be directly applied to the study of ToM. The work in this proposal seeks to bridge the gap between techniques traditionally used to study ToM and the computational modeling that has proven so successful in the field of decision-making. Specifically, I will develop a novel computational ToM task (cToM) designed to meet the criteria of traditional ToM tasks while facilitating the construction of rigorous mathematical models for describing the ToM computations underlying the representation of others' beliefs and intentions. In three specific aims I will: 1) Develop and test different computational models of ToM in my cToM task, characterize individual differences in cToM performance in healthy participants, and cross-validate performance on the cToM task with traditional measures of ToM. 2) Combine the cToM task and functional Magnetic Resonance Imaging (fMRI) to identify the specific ToM computations performed by ToM-related brain regions in healthy participants and employ functional connectivity analyses to characterize functional interactions between brain regions in the ToM network. 3) Employ computational modeling of ToM in the cToM task to quantify specific behavioral and neural dysfunction in ToM processing in high-functioning adults with autism spectrum disorder. To complete these research aims will require extensive training in a series of techniques that are novel to me including: development and testing of computational models of DM, advanced computational fMRI methods and functional connectivity analyses, conducting ASD research and the administration of specific ASD assessment tools. In addition, this proposal outlines a series of concrete steps to ensure my continued career development and prepare me for the transition to having my own independent laboratory, including: training in paper and grant writing, preparation of faculty position and R01 grant applications, and the development of course curriculae. The protected, mentored time requested in this proposal is crucial in order to enable me to acquire these skills and develop my research portfolio. Combined, the research and training described in this proposal will provide me with the necessary background and experience to achieve my career objective of establishing an independent line of research aimed at integrating concepts and techniques from neuroscience, decision- making, cognitive psychology, and social psychology to provide a detailed computational account of Theory of Mind processing. PUBLIC HEALTH RELEVANCE: These studies will provide mentored training and research to develop a novel computational framework for understanding the neural basis of Theory of Mind (our natural ability to infer the mental states of other people). This computational framework could help to better characterize distinct causes of variation in social cognitive abilities both i healthy individuals and those with social disorders such as autism.